Limited Evidence of an Association Between Language, Literacy, and Procedural Learning in Typical and Atypical Development: A Meta-Analysis.

The ability to extract patterns from sensory input across time and space is thought to underlie the development and acquisition of language and literacy skills, particularly the subdomains marked by the learning of probabilistic knowledge. Thus, impairments in procedural learning are hypothesized to underlie neurodevelopmental disorders, such as dyslexia and developmental language disorder. In the present meta-analysis, comprising 2396 participants from 39 independent studies, the continuous relationship between language, literacy, and procedural learning on the Serial Reaction Time task (SRTT) was assessed across children and adults with typical development (TD), dyslexia, and Developmental Language Disorder (DLD). Despite a significant, but very small, relationship between procedural learning and overall language and literacy measures, this pattern was not observed at the group-level when examining TD, dyslexic, and DLD groups separately. Based on the procedural/declarative model, a positive relationship was expected between procedural learning and language and literacy measures for the typically developing group; however, no such relationship was observed. This was also the case for the disordered groups (ps > .05). Also counter to expectations, the magnitude of the relationship between procedural learning and grammar and phonology did not differ between TD and DLD (ps > .05), nor between the TD and dyslexic group on reading, spelling, and phonology (ps > .05). While lending little support to the procedural/declarative model, we consider that these results may be the consequence of poor psychometric properties of the SRTT as a measure of procedural learning.